Vehicles equipped with a collision preparation system or CPS utilizes one or more sensors to monitor the path of travel of the vehicle for a potential obstacle, and to ascertain the distance and closing rate to such an obstacle. If the CPS determines that a collision is imminent or likely, various autonomous or semi-autonomous control actions can be executed to thereby minimize the probability of such a collision, or to at least mitigate the effects of a resultant collision. For example, seat belt tension can be automatically adjusted in a limited CPS, and/or an audible alarm can be activated to alert the driver and other vehicle occupants to the imminent collision. In a more advanced CPS, a hydraulic braking system can be stroked or readied so that the braking system can respond more rapidly when the driver ultimately depresses the brake pedal in response to the obstacle. In a highly advanced CPS, at least some degree of autonomous braking response can be used to help slow the vehicle when an obstacle is detected within a predetermined range on the road surface.
A typical CPS relies almost exclusively on radar-based remote scanning devices that utilize long range capabilities. As will be understood by those of ordinary skill in the art, using a long range radar system an electromagnetic (EM) pulse can be transmitted toward the obstacle, with the echo, return, or signature of the EM pulse being returned to the radar device. Interpretation or classification of the signature provides the necessary range and closing rate data required to prepare the CPS for action.
Radar devices offer a relatively extensive detection range of as much as approximately 150-200 meters from the vehicle, and therefore are highly practical scanning devices. However, there are certain inherent limitations in the types of obstacles that can be accurately detected and classified by a radar device. As a result, under certain circumstances the CPS may take an action, or may forego an action, in response to an inaccurately or less than optimally evaluated collision risk, particularly for certain potential off-road obstacles.